We aim to develop tools for the precise ultrastructural localization of macromolecules important in neurotransmission, to define their interactions in biochemical, physiological, and pharmacological terms, and to apply this knowledge to the understanding and management of human neurological disorders, such as Parkinsonism, Huntington's disease, epilepsy, and spasticity. Recently with immunocytochemical techniques we have been able to visualize glutamic acid decarboxylase, the rate-limiting enzyme in biosynthesis of gamma-aminobutyric acid (GABA), in light and electron microscopic preparations of the CNS. Coupled with similar procedures for enzymes that are rate-limiting in the biosynthesis of other transmitters, this will give detailed information of interrelationships of various neuronal systems at specific sites. Efforts will be made to improve the penetration of antibody to sites of antigen, eliminate fixation artifacts, achieve visualization of several antigens in small regions, and then to apply these procedures to various problems in rodent CNS and eventually to normal and abnormal human neural tissue. We will develop procedures for isolating from one source and characterizing fully as proteins, the enzymes that are rate-limiting in the biosynthesis of known transmitters in the vertebrate CNS and the receptors for the transmitters. Quantitative immunochemical tools will be developed to facilitate relevant microchemical and microcytochemical studies of the CNS. Physiological studies will establish and characterize vertebrate and invertebrate systems in which quantitative studies can be made of the action of GABA on membranes, and specific GABA agonists and antagonists will be sought. The latter and binding studies of GABA on brain particles will be used in developing agents to enhance potency of GABA synapses in clinical conditions in which neural inhibition may be inadequate. Biochemical and neurochemical studies are planned to develop strategies for the manipulation of the GABA system in vivo, ranging from repression and derepression of relevant enzymes to the administration of substances that may be specific precursors of sequestered pools of amino acid neurotransmitters.